[yocto] Kernel config incremental modification not working.

[Bruce Ashfield]

On 2016-12-08 09:06 AM, Bent Bisballe Nyeng wrote:
> Hi list
>
> I am working on a project based on the iMX6UL-EVK using the meta-fsl-arm
> layer for the kernel.
> In a local layer I have a bbappend recipe containing a patch for an
> extra kernel feature (a framebuffer device) in that kernel as well as a
> .cfg enabling said feature.
> The bbappend recipe is located in
> recipes-kernel/linux/linux-fslc-imx_%.bbappend and looks like this:
> FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
>
> SRC_URI += " \
>         file://0001-mxc-4.1.patch \
>         file://ST7789S.cfg \
> "
>
> KERNEL_DEVICETREE = "imx6ul-14x14-evk.dtb"
>
> The .cfg is located in recipes-kernel/linux/linux-fslc-imx/ST7789S.cfg
> and looks like:
> CONFIG_FB_MXS_ST7789S_QVGA=y
>
> The 0001-mxc-4.1.patch patch is correctly applied but the .cfg is either
> ignored or overwritten by some later buyild step since the resulting
> .config after kernel compilation contains:
> # CONFIG_FB_MXS_ST7789S_QVGA is not set
>
> I have tried finding the script in the build/.../temp folder that takes
> care of the .cfg file patching but have not been able to find anything
> useful.
>
> Any hints as to where I should start looking for a solution?

Fragment processing using the kernel tools + auditing is only currently
available to kernel recipes that use the kernel-yocto bbclass. That
opt-in requirement was to ensure that existing recipes and workflows
weren't broken by the new features.

Last time I checked, the meta-fsl* kernel recipes don't use the
kernel-yocto bbclass, so the fragment would be ignored.

I'm taking the processing of fragments and making it universally
available in the upcoming 2.3 release, so what I just described
won't be an issue for much longer.

In the mean time, you have a few options:

  - in your bbappend, add "inherit kernel-yocto" and the processing
    of fragments will be enabled (I can't say that I've tested
    it against that recipe .. but the entire point of the new tasks
    is that they are transparent/don't break existing worflows)

  - carry a defconfig in your layer, and add it to the SRC_URI. That
    defconfig would be the existing kernel recipe's defconfig + your
    options

  - write a custom task that runs before configuration to add your
    options (cat, merge, etc, etc).

I wouldn't really suggest the custom task route, but it is a valid
option, so I put it in my list.

The quickest is probably the defconfig option, and then the new
inherit. If you had issues with the inherit, I could lend a hand to
debug what is wrong .. since I'll run into it eventually with my
feature work for the 2.3 release.

Bruce


>
> Kind regards
> Bent Bisballe Nyeng
>